Using the same tag will not solve this problem. The aim of group collection could be help teachers to find the requested materials. A group of teacher could be collect the materials, which are interesting for them. For example the group of teachers (for example geometry teachers) can collect good math materials. This group collections could be a way to quality management, which is very important for teachers (ask them, if you don't believe me). With this group collection it would be possible that math teachers make a group, which qualify the materials. If you want to find really good quality hungarian math lessions, you could search in the collection of this group. I think it would be a very good feature.